Use entities in BackendClasses

pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:js_runtime/shared/embedded_names.dart';
 import 'package:kernel/ast.dart' as ir;
 
 import '../common.dart';
 import '../common/names.dart';
 import '../compiler.dart';
@@ skipping 285 matching lines @@
         // String is indexable but not iterable.
         !mask.satisfies(_backend.helpers.jsStringClass, closedWorld);
   }
 
   bool isFixedLength(TypeMask mask, ClosedWorld closedWorld) {
     if (mask.isContainer && (mask as ContainerTypeMask).length != null) {
       // A container on which we have inferred the length.
       return true;
     }
     // TODO(sra): Recognize any combination of fixed length indexables.
-    if (mask.containsOnly(closedWorld.backendClasses.fixedListImplementation) ||
-        mask.containsOnly(closedWorld.backendClasses.constListImplementation) ||
+    if (mask.containsOnly(closedWorld.backendClasses.fixedListClass) ||
+        mask.containsOnly(closedWorld.backendClasses.constListClass) ||
         mask.containsOnlyString(closedWorld) ||
         closedWorld.commonMasks.isTypedArray(mask)) {
       return true;
     }
     return false;
   }
 
   TypeMask inferredIndexType(ir.ForInStatement forInStatement) {
     return TypeMaskFactory.inferredTypeForSelector(new Selector.index(),
         typeOfIterator(forInStatement), _globalInferenceResults);
@@ skipping 791 matching lines @@
       JumpTarget continueTarget =
           astAdapter.getJumpTarget(switchCase, isContinueTarget: true);
       assert(continueTarget is KernelJumpTarget);
       targetIndexMap[continueTarget] = switchIndex;
       assert(builder.jumpTargets[continueTarget] == null);
       builder.jumpTargets[continueTarget] = this;
       switchIndex++;
     }
   }
 }